Abstract
In a head positioning control system of hard disk drives, multi-stage notch filters are used in order to stabilize mechanical resonant modes of the controlled system. Conventionally, the parameters of these filters are tuned by try and error method in advance of the mass production of HDDs. By this tuning method, it is difficult to prevent the occurrence of defective products caused by the variation of mechanical resonant modes. In order to overcome this problem, we have developed an auto-tuning method of these parameters in production line by multi-objective optimization.